Treatability and Variability of Marine Chronic Toxicity in Dissolving Sulfite Mill Effluent, 1997 Environmental Conference Proceedings

West Coast U.S. pulp mills with marine or estuarine wastewater discharges are being confronted with marine chronic toxicity discharge limits that are very difficult to meet. In an effort to comply with these toxicity limits, the Ketchikan Pulp Company dissolving sulfite mill conducted toxicity treatability testing to evaluate the effects of several process and wastewater treatment modifications on effluent toxicity. These efforts generated a large amount of marine chronic toxicity data, which is presented here in the hope that it will be useful to other marine discharge mills facing similar regulation. The marine chronic bioassay tests conducted were the echinoderm (sea urchin) sperm cell test and the bivalve mollusk (blue mussel or Pacific oyster) larval development test. The levels of toxicity measured by the three test organisms increased in the order: sea urchin < blue="" mussel="">< pacific="" oyster.="" the="" average="" reduction="" efficiency="" of="" marine="" chronic="" toxicity="" across="" secondary="" treatment="" in="" bench-,="" pilot-,="" and="" mill-scale="" tests="" averaged="" 34-77%="" for="" sea="" urchins="" and="" 25-58%="" for="" blue="" mussels.="" pacific="" oyster="" toxicity="" showed="" no="" consistent="" response="" to="" biological="">